Costco

=== SEC Form 4 — Statement of Changes in Beneficial Ownership === Document Type: 4 Period of Report: 2026-09-10 10b5-1 Pre-arranged Plan: No --- Issuer --- Name: COSTCO WHOLESALE CORP /NEW (COST) CIK: 0000909832 --- Reporting Owner --- Name: Adamo Claudine CIK: 0001916124 Role: Officer (Executive Vice President) --- Non-Derivative Transactions --- [Transaction #1] Security: Common Stock Date: 2026-09-10 | Code: A (Grant or award) Shares: +4,129 | Price: $0.00 Shares Owned After: 10,250.195 | Ownership: D (Direct) Footnotes: [F1] Grant was initially made on October 22, 2025, subject to performance conditions concerning fiscal 2026, which have been deemed satisfied by the Compensation Committee of the Board of Directors. The earned awards vest 20% on the first anniversary of the grant date and an additional 20% vest over each of the ensuing four years based on continued employment with the Company. In addition, under the 2019 Incentive Plan, employees are eligible for accelerated vesting upon the anniversary of their 25th, 30th and 35th years of service. [F2] Not applicable. Grant of Restricted Stock Units. [Transaction #2] Security: Common Stock Date: 2026-09-10 | Code: F (Payment of exercise/tax) Shares: -916.685 | Price: $902.38 Total Value: $827,198.21 Shares Owned After: 9,333.51 | Ownership: D (Direct) --- Footnotes (Complete Index) --- F1: Grant was initially made on October 22, 2025, subject to performance conditions concerning fiscal 2026, which have been deemed satisfied by the Compensation Committee of the Board of Directors. The earned awards vest 20% on the first anniversary of the grant date and an additional 20% vest over each of the ensuing four years based on continued employment with the Company. In addition, under the 2019 Incentive Plan, employees are eligible for accelerated vesting upon the anniversary of their 25th, 30th and 35th years of service. F2: Not applicable. Grant of Restricted Stock Units. --- Signature --- /s/ /s/ Alejandro Torres, Attorney-in-Fact (2026-09-14)